Visuo-motor related time (VMRT), which is calculated by subtracting the latency of motor-evoked potentials (MEP) from pre-motor time (PMT) as measured by electromyography for simple reaction tasks, reflects the time elapsed from visual stimulation to the motor cortex through the visual cortex. We aimed to determine whether observation training to a light signal shortens the VMRT. Fourteen healthy male subjects were divided into 2 groups: a training (TR) group that underwent training consisting of careful observation of a visual signal in a relaxed state, and a control (CONT) group that did not undergo any training. The TR group underwent the observation training for 4 weeks. Both groups performed the same response time test, which involved isometric abduction of the right index finger as quickly as possible in response to a visual signal, before (Pre-test) and after (Post-test) the training period. PMT, MEP latency, and VMRT were measured at each test. PMT, VMRT but not MEP latency were significantly shorter at Post-test than at Pre-test in the TR group. In addition, relative reduction in VMRT by training showed a positive correlation with Pre-VMRT. Coefficient of determination was 0.71.
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